iv had dis happen to me before. somehow i fixed it. i think i has to do to where other people live in real life if it is="local" but i do it perfectly fine

look, the problem is your addons if you open console this is say error and some player cannot download it this why

引用自 Michael Jackson：

look, the problem is your addons if you open console this is say error and some player cannot download it this why

and if i dont have any addons enabled or on ?

If you start a map through the console, they won't be able to connect. You need to go through the multiplayer menu instead.

引用自 BenJamin'：

If you start a map through the console, they won't be able to connect. You need to go through the multiplayer menu instead.

i dont use console

when you create it, type sv_consistency 0 in the console. make sure its a local server

Just as a note for anyone else who may come across this problem, perform the following steps.
[1. ]Create a text file document and rename it to autoexe.cfg (Change .txt to cfg)
[2.] Open the file and list the following commands, go down a line for each command. sv_consistency 0
sv_pure 0
sv_region 0 ( change number to your area for best connection (0) US - East (1) US - West (2) South America (3) Europe (4) Asia (5) Australia (6) Middle East (7) Africa (255) World (default)
[3.] Save file and place in C:\Program Files (x86)\Steam\steamapps\common\Left 4 Dead 2\left4dead2\cfg
[4.] Type exec autoexe.cfg in your console each time you launch the game. or to avoid typing it each time type
bind "Insert key you never use here such as F8" "exec autoexec.cfg"
[5.] Enjoy and make sure you host a local server.

peacestika i have no idea what any of that means help please?

@fatnatpat , Please take your time and reread the post again. There are step by step instructions on how to make sure everything from the admin system works. I have simplified it as much as possible.